All stainless steels are resistant to oxidation, but the types and proportions of impurities inside are different, and the ability to resist acid corrosion is also different (sometimes we see that the surface of some stainless steels is still rusted, because it is corroded by acid). In order to distinguish the acid corrosion resistance of these stainless steels, different grades are specified for stainless steels.
304 and 316 are the more common stainless steel grades in our lives. We can simply understand that the larger the number of the grade, the stronger the acid corrosion resistance of stainless steel.
There are stainless steels with poorer acid corrosion resistance than 304 stainless steels, but those stainless steels cannot meet food contact requirements. Common daily food may corrode stainless steel. Not good for stainless steel, and even worse for the human body. For example, stainless steel railings are commonly used 201 stainless steel.
